Our increasing appreciation of 1) tumor genetic and cellular heterogeneity, 2) the recent descriptions of cancer stem, endothelial progenitor, &myoepithelial cells, among others, and 3) disparate responses to treatment even for histologically similar tumors;raise fundamental questions as to the relative contributions of various tumor cellular subsets to the biologic behavior of a tumor. However, technologies permitting the prospective characterization of discrete tumor cellular elements and recovery of selected viable cells from a tumor have yet to be developed. We have developed a novel nanotechnology consisting of an array of microfabricated SU8 polymer elements that permits the isolation and recovery of individual adherent cells. This advanced nanotechnology combined with multicolor immunofluorescence and advanced confocal microscopy enables us to propose application of this technology to the simultaneous identification, recovery, and evaluation of selected molecular profiles from viable primary adherent cell populations representing the various cellular elements within individual tumors. The HYPOTHESIS for these studies is that the pallet array nanotechnology will permit identification, enumeration, and recovery of the following individual cellular tumor elements: cancer stem, endothelial progenitor, myoepithelial, epithelial, and inflammatory cells leading to the molecular characterization of these cellular subsets within individual tumors and will be tested by pursuing the following Specific Aims: AIM #1. Refine the pallet array for maximum cell capture, detection, and recovery of tumor cellular elements. AIM #2 Apply pallet array to Fine Needle Aspirate (FNA) samples of primary breast tumors to identify and isolate individual cells from discrete tumor cellular elements. AIM #3 Establish feasibility of molecular analysis of recovered individual rare cells, e.g. single cell RT-PCR. These studies represent a convergence of biomedical engineering, advanced laser optics, cell biology, immunology, and clinical oncology and will drive future studies to address fundamental biological and clinical questions.